Material retained for purposes of national security[4] 10.

Material retained with consent[2] 12.

Materials that remain paramagnetic at 0K, by contrast, may have many nearly-degenerate ground states (for example, in a spin glass), or may retain dynamic disorder (a quantum spin liquid).

Materials with extremely high resistivity, such as Teflon, may retain excess charge for many hundreds of years.

Material retained pending investigation or proceedings[0] 3.